Biochemical properties of endothelin converting enzyme in renal epithelial cell lines

Abstract This is the first report clearly demonstrating the presence of endothelin (ET) converting enzyme (ECE) in non-vascular cells (renal epithelial cell lines, MDCK and LLC-PK 1 ). ECEs derived from these epithelial cells were very similar to the endothelial ECE in the following biochemical properties: 1) The optimum pH was 7.0; 2) the Km value for big ET-1 was approximately 30 μM; 3) the enzyme was potently inhibited by EDTA, o -phenanthroline and phosphoramidon; and 4) the enzyme did not convert big ET-2 or big ET-3. These data suggest that phosphoramidon-sensitive ECE is involved in the processing of big ET-1 to ET-1 in the renal tubule.